This invention relates to a vacuum system for recovering particulate materials and more particularly to such a system having an improved ejector device as a component thereof.
In the chemical process industry, there often is used a type of equipment in which particulate materials may be dumped for further handling, commonly referred to as a bag dump station. Such stations generally consist of a hopper having an inlet opening through which bags of particulate material may be dumped manually, and an outlet opening typically communicating with a pneumatic conveying line, and a filter unit disposed within the housing of the station and in communication with the interior of the hopper which operates to draw airborne particles in the vicinity of the hopper into the interior of the hopper.
In the use of such dump stations, it has been found that spillage of particulate material often occurs or that the particular material to be dumped is contained in large drums which often are too heavy to be manually lifted and dumped as with smaller bag material. In an effort to recover such spilled material and also to accommodate the handling of drums too heavy to be lifted and dumped, a vacuum system has been developed utilizing an ejector for vacuuming spilled material and material contained in heavy containers. An example of such a vacuum system and ejector is illustrated and described in U.S. Pat. No. 5,769,572.
Although the type of vacuum system and ejector disclosed in the aforementioned patent have been found to be highly effective in handling particulate material which has been spilled or contained in a heavy drum, the ejector therefor has been found to be comparatively costly to fabricate and mount on the hopper of such dump stations. Furthermore, because of the tubular construction of such ejectors, it has not been possible to utilize abrasive-resistant materials in fabricating such ejectors, which are advantageous and preferable to use because of the abrasive properties of many particulate materials with which such ejectors have been used.
It thus is the principal object of the present invention to provide an improved ejector and a system utilizing such an ejector, which may be more economically fabricated and mounted, and will be effective in handling abrasive materials. The aforestated objective of the invention is accomplished by forming such ejectors with flat pieces of metal welded together so that each of the diverging, restricted or throat and converging sections of the ejector defining a venturi have rectangular cross sectional configurations. The ejector preferably includes a base plate mountable on a wall of the station hopper, a first set of plates joined together and with the base plate defining a converging chamber, a second set of plates joined together and with the first set of plates and the base plate defining a restricted chamber communicating with the converging chamber, and a third set of plates joined together and with the second set of plates and the base plate defining a diverging chamber communicating with the restricted chamber. One of the plates is provided with a first inlet opening through which a stream of pressurized fluid may be ejected into the converging chamber, one of the plates is provided with a second inlet opening through which the fluid having entrained therewith a particulate material to be conveyed may be suctioned, and one of the plates has an outlet opening communicable with the diverging chamber. The device is mounted on the hopper of the dump station so that the outlet of the diverging chamber of the device registers with an opening in the hopper so that material conveyed through the ejector will be discharged into the interior of the hopper. The component plate sections of the ejector preferably are formed of an abrasive resistant metal to resist the erosive effect of abrasive materials conveyed through the ejector, and are welded together to facilitate the fabrication and mounting of the ejector.